Our previous work on regulation of cell division led us to look at cyclic AMP metabolism in marine eggs and in cells in culture. The properties of sea urchin egg adenyl cyclase have been investigated and we will now follow this enzyme through early development. Similarly for the cyclic AMP phosphodiesterase. In addition a systematic study of CAMP levels in eggs will investigate cyclic AMP and calcium effects on morphology and cell division rates in serum free media. For this we will use CHO cells and LS cells in artificial media in which calcium and cyclic AMP levels are varied. We will also attempt to measure CAMP production and breakdown in vivo by a method which has been successful in measuring these parameters for RNA. The formal similarities to the CAMP problem look promising and if successful, would allow us to look at adenyl cyclase and phosphodiesterase activities without first isolating the enzymes.